Surgical margin status among men with organ-confined (pT2) prostate cancer: a population-based study

Background: Following prostate cancer surgery, positive surgical margin (PSM) status varies among institutions and there is evidence that high-volume surgeons and centres obtain better oncological results. However, larger studies recording PSM for radical prostatectomy (RP) are from large centres of excellence and not population-based. Cancer Care Ontario undertook an audit of pathology reports to determine the province-wide PSM rate for pathological stage T2 (pT2) disease prostate cancer and to assess the overall and regional-based PSM rates based on surgical volume to understand gaps in quality of care prior to undertaking quality improvement initiatives. Methods: Data were extracted as part of the Pathology Project Audit data output (2005, 2006). Pathology reports were submitted to Cancer Care Ontario by Ontario hospitals electronically via the Pathology Information Management System. An experienced cancer pathology coder extracted the PSM data from eligible RP cancer specimen pathology reports. Only reports that provided a pathological stage were included in the analysis. Biopsy and transurethral resection of the prostate reports were excluded. A convenience sample of 1346 reports from 2006 and 728 from 2005 were analyzed. Regression analysis was performed to assess volume-margin associations. Results: The median province-wide surgical PSM rate for pT2 disease was 33%, ranging 0-100% among 43 hospitals where RP volumes ranged 12-625. There was no significant correlation (p > 0.05) between volume and PSM by logistic regression with variable odds ratios (95% confidence interval [Cl]) for PSM by quartile (1(st) = 1.66 [0.93-2.96]; 2(nd) = 0.97 [0.58-1.62];.3(rd) = 1.44 [0.91-2.29]) compared to the highest volume last quartile. Mean PSM rates between community and teaching hospitals were not significantly different. Conclusions: The province-wide PSM rate for pT2 disease prostate cancer undergoing RP is higher than those published from centres of excellence. Results from larger volume centres were not statistically significantly better, which contradicts previously published data. Factors, such as individual surgeon, patient selection, pathological processing and interpretation, may explain the differences.